The Inspector’s Notebook #15
Stay away from CCA

For fence posts, trellises, or any other application coming in contact with soil or livestock, Jim says, stick with naturally rot-resistant woods like cedar, hedge or black locust

By Jim Riddle

Editor’s NOTE:

Certified organic farmers do an odd thing – they pay people to visit their farms with a critical eye to assure they are adhering to every aspect of the USDA’s national organic standard.

The farmers should already be trying to produce, harvest and market their organic crops, livestock and related products by these rules. The on-farm review of fields, facilities and records by an approved inspector sent by the farmer’s accredited organic certifier is the critical point in confirming that the farmer and the farm meet the organic standards – and can prove it to anyone who needs to know.

The visits are pivotal for applying farmers to become certified, and for certified farmers to keep that certification. For the good of organics, we want to help build the foundation for effective inspection visits. We’ve asked Jim Riddle to provide an inspector’s inside view to help farmers understand an inspector’s role, responsibilities and limitations.

In the months ahead, Riddle will elaborate on many items to help farmers understand regulations that apply to them, and how to document their compliance.

Jim Riddle has been on hundreds of farms in the inspector role, and he’s been inspected himself during his time as a farmer. His leadership in bringing professional training to inspectors helped to earn greater acceptance of organic farming in the U.S. He serves as vice-chair of the National Organic Standards Board, which advises the USDA on organic agriculture policies and regulations. He has been an organic farmer, gardener, inspector, educator, policy analyst, author, and consumer.

Jim Riddle serves as vice-chair of the USDA’s National Organic Standards Board and organic policy advisor for NewFarm.org. He was the founding chair of the Independent Organic Inspectors Association (IOIA).

September 1, 2005: I was working on my grape arbor the other day and noticed that some of the posts need to be replaced. We use the grapes to make jelly, juice, and homemade wine. We don’t sell any of the grapes or grape products, but we still follow organic standards and we have the grapes listed on our Organic System Plan.

So I need to use rot-resistant posts, but according to organic regulations I can’t use posts treated with copper chromium arsenate or creosote. This is a common dilemma faced by many organic vegetable, fruit and livestock producers.

The National Organic Standards, in section 205.206(f) state, “The producer must not use lumber treated with arsenate or other prohibited materials for new installations or
replacement purposes in contact with soil or livestock.”

My posts will be used for replacement purposes, and they will contact the soil, so I must not use lumber treated with arsenate or other prohibited substances. How do I know which types of posts on the market are treated with prohibited substances?

Pennsylvania Certified Organic (PCO) reported in their Spring 2005 newsletter, Organic Matters, that they reviewed four wood treatments and found that all contained prohibited substances. They were:

  • Natural Select® Wolmanized Wood
  • Copper Azole Wood Treatment (CBA)
  • Preserve® and Preserve Plus® (AQC)
  • Akaline Copper Quaternary Ammonium

So now I know what I can't use—what can I use?

ATTRA (Appropriate Technology Transfer to Rural Areas) also has an informative booklet, titled Organic Alternatives to Treated Lumber, posted at http://www.attra.org/attra-pub/lumber.html.

According to the ATTRA publication, chromated copper arsenate (CCA), often referred to as “pressure-treated lumber,” is most commonly available in retail outlets. The CCA mixture, which contains copper, arsenic, and chromium compounds, is dissolved in ammonia and then forced, under high pressure, deep into the wood.

Arsenic, chromium, and copper do leach from treated wood. Arsenic can collect in the soil under most CCA-treated wood applications. Burning CCA-treated wood volatilizes some of the arsenic, but the ash remaining is technically a hazardous waste. Disposal of CCA-treated wood to landfills may be potentially dangerous because as the wood rots in the landfills, the metals are released and may pose a threat to groundwater.

Recent studies have shown that arsenic can be absorbed through the skin from contact with treated wood. The results of prolonged exposure to arsenic can include vomiting, diarrhea, nerve damage, blood vessel damage, and heart rhythm dysfunction (Rodale, 2000). Arsenic is also an extremely potent carcinogen, and chromium is a suspected carcinogen.

Because of the health concerns surrounding CCA-treated wood, the U.S. Environmental Protection Agency implemented a ban on its manufacture and sale for residential applications effective January 1, 2004. Many of the "alternative" treated wood products (such as those listed above that were tested by PCO) also contain substances prohibited in organic systems, however.

Cooperative Extension of the University of Nebraska-Lincoln has a publication, Native Wood Fence Posts (Schmidt and Kuhns, 1990), that lists the expected lifespan of many untreated wood species used for fence posts, along with information on some of the advantages of seasoning posts before use. See http://ianrpubs.unl.edu/forestry/g314.htm.

According to the Nebraska publication, the best species for use as fence posts without treatment are osage orange, also known as hedge (>35 years), black locust (>20 years), and eastern red cedar (>20 years).

Besides untreated wood fence posts, other options include plastic, plastic/wood composites, steel T–posts, steel pipe, concrete, fiberglass, or even concrete–filled plastic pipe. These fence posts will vary in cost, availability, and practicality for each specific fencing need.

Many plastic fence posts are made from recycled plastic containers. They come in various lengths, dimensions, and colors; can be stapled, drilled, or cut like wood; and are self-insulating for electric fencing.

If you already have treated wood posts in your field, garden, arbor, or orchard, you are “grandfathered in.” However, if the treated wood comes in direct contact with crops or livestock, it may present a contamination risk, and you might need to remove or replace it. As always, check with your certifying agent.

When it's time to replace wood treated with prohibited substances or put in new posts, you must use approved materials in order to follow the organic standards.

Osage orange doesn’t grow in my area, but we have plenty of eastern red cedar. We have been clearing a savannah prairie of red cedar and buckthorn, so I’ll use the red cedars for posts in my vineyard.

This material was developed with the support of the U.S. Department of Agriculture through the Risk Management Agency, under Agreement No. 031E08310147.